Process for purifying metals and the product produced thereby



wIL Im .1. MEBTEN, or rxrrsnunen, PENNSYLVANIA, nssm'non 'ro wnsrmciiousr.

Patented Jan. '27, 1931 UNITED STATES PATENT OFFICE ELECTRIC & MANUFAGTU'RING'COMPANY, A CORPORATION OF PENNSYLVANIA Y PROCESS FOR PURIFYINGMETALS AND'THE PRODUCT PRODUCED THRREDY No Drawing.

My invention relates to alloys and specifically to non-ferrous alloys inwhich lead is sition.

Alloys containing lead 10% to 28%, tin

2% to 10%, and the remainder copper and minor impurities have hitherto been made. Such bronze alloys have been used extensively for bearings as the alloy structure consists of lead or a soft lead alloy existing in and dispersed in a matrix of harder metal or alloy consisting mainly of copper. The soft selectively segregated particles of lead in the harder matrix provides the kind of surface in bearings which will compensate in some measure for oil lubrication when the film of lubricating oil becomes temporarily broken, provided the soft metal or lubricating constituent is more or less uniformly distributed throughout the matrix.

Heretofore, bearings which were made of such alloys have not been uniformly satisfactory because of the lack of uniform distribution of the soft l'ubricating metal in. the harder matrix and because of segregation of the lead. The segregation of the lead results in an excess of lead in certain portions of the structure and too little or no lead in other portions.

I have discovered that when the alloy is treated in the molten state with calcium carbide (CaC the lead is caused to disseminate and to be mechanically dispersed into extremely small spheroidal bodies throughout the matrix, and that segre ation of the lead is prevented thereby. e bodies of lead appear to be slightly harder, they are more tenacious and less friable than metallic lead and a tight efiicient bonding with the cuprous metal crystals exists.

Application filed June 4, 1927. serial'no. 196,635.

When the melted alloy is treated in accordance with my process, there is an evolution of gas comprising oxides of carbon which are derived from the combination of the carbon in'the calcium carbide with the oxides in the alloy. A dross or slag-like material that contains silicates, sulphates and other impurities is formed and rises to the surface, of the melt. It'would be expected that the elimination of the hard compounds comprising oxides andother non-metallic compounds in the alloy would soften it, but on the contrary, the alloy is noticeably hardor than untreated alloys of like composition. It is believed that the improved properties of the alloy is due to the presence of calcium as a,-calci'um-lead compound as well as to the existence of the lead in a new physical character with respect to the matrix.

The hardened alloy is particularly useful for bearings'sinceit is less apt to be distorted when it is subjectedto a heavy pressure, therefore,a bearing made of the alloy will retain its intended shape and proportions for a long time in service. The lead operates to impart the propertyof lubrication to the alloy as it is uniformly distributed and dispersed throughout the structure. Consequently', the alloy is a material that is re I provide an alloy consisting of lead 10% to 28%, tin 2% to 10% and copper and imbearings that are made of my purities 88% to 62%. The alloy is made by I melting the constituents together in the desired proportions. When the alloy is melt ed, orrif preferred, during the melting of 1 the alloy, I add calcium-carbide in the proportion of about one pound of carbide to fifty pounds of the alloy. The calcium-carbide reacts with the impurities, such as oxides and produces gases and slag-like materials that separatefrom the metal. The calcium' compounds of slag-like material are lighter than the metallic compounds of lead 4 and they can be removed from the surface of the melt with the dross. v

In' addition to its cleanin or scavengering action, calcium-carbi e appears to harden the lead and to cause a spheroidal dispersion of the lead throughout the alloy. It

a pears from microscopic examination thatt ere has been a physical change in the lead constituent and t at it is disseminated ur'a matrix of the stronger and harder metal in fine well distinguished globules which occur as definite distinct spheroidal aggre ates of metallic crystals disposed among t e copper-metal crystals and not as an accumulation or segregationof lead of planiform or inde 'te form and amount at the crystal boundaries, such as the segregation occur- 'rin in untreated alloys of like chemical ana ysis.

Although I have described a specific alloy and a specific modification of my process, do not wish to be limited thereto, as a similar di rsion of the'soft insoluble constituent 0 other non-ferrous alloys may be produced by utilizing my invention. Other modifications of my invention will suggest themselves toqthose skilled in the art wit out deiplfirting from the spirit of my invention as de I ed by the appended claims.

I claim as my invention:

1. In the process of preparing alloys comprisin at least 62% copper a small percentag; 0 tin and the remainder lead, the step w 'ch comprises adding calcium carbide to the alloy when it is in at least a partially molten state 'for the dpurpose of causing a throughout the cop-' per-tin matrixand preventing its segrega-' tion during the subsequent cooling of the dispersion of the lea alloy.

2. In the process of preparing alloys comprisin at least 62% cop er, 2% to 10% tin and t e remainder lea the steps which comprise melting the constituents of the alloy together, adding calcium carbide to the melted alloy and then cooling the alloy.

3. In the process of preparmg alloys comprisingfrom 62% to 88% copper, 2% \to 10% tm and the remainder lead and minor impurities, the steps which com rises melting the-ingredients together, adding calcium carbide to the molten alloy, removing the impurities from the surface of the-metal and then cooling the alloy.

In the process of pre af'mg alloys compnsmg 10% to 28% lea 2% to 19% tin and 62% to 88% copper and minor impurities, the steps whic comprise melting the ingredients together, adding calcium carbide to the molten alloy and then permitting the alloy to cool. In testimony whereof, I have hereunto subscribed my name this 27th day of May,

J. MERTEN, 

